Preferred embodiments of the invention relate to a water-cooled cylinder head for a multicylinder internal-combustion engine having a cylinder head housing comprising charge cycle ducts, passage bores for receiving cylinder head screws, valve stem guides for inlet and outlet valves, part-spherical combustion chamber caps which are bounded by a water cooling jacket on a side facing away from a respective combustion chamber, and one spark plug dome respectively whose opening leads to the combustion chamber of the respective cylinder.
A water-cooled cylinder head of the above-mentioned type is known, for example, from German Patent Document DE 199 55 431 A1.
In the case of motor vehicles, it is generally endeavored to reduce the overall weight of the vehicle, among other things, for saving fuel. For this purpose, light-metal alloys are increasingly used, for example, for the crankcase and cylinder head housing for engines. However, particularly in the case of high-performance engines, temperature peaks occur because of the high specific performance in the cylinder head, particularly in the area between the outlet valves or between the outlet valve and the spark plug. This results in temperature stress in the material and, in connection with external loads, may lead to permanent deformations in the seat ring area and thus to valve leakiness.
It is therefore an object of the invention to overcome the above-mentioned disadvantages.
This object is achieved by providing water-cooled cylinder head for a multicylinder internal-combustion engine, having a cylinder head housing comprising charge cycle ducts, passage bores for receiving cylinder head screws, valve stem guides for inlet and outlet valves, part-spherical combustion chamber caps which are bounded by a water cooling jacket on a side facing away from a respective combustion chamber, and one spark plug dome respectively whose opening leads to the combustion chamber of the respective cylinder, wherein, for reinforcing the cylinder head housing and/or for supporting the part-spherical combustion chamber caps, a rib structure is integrated in the cylinder head housing.
As a result of the fact that a rib structure is integrated in the cylinder head housing, the cylinder head housing constructed of light metal can be reinforced and the highly temperature-stressed part-spherical combustion chamber caps can be effectively anchored in the cylinder head housing. By means of these structural measures, it is ensured that, despite a high temperature stress, the cylinder head remains dimensionally stable, particularly in the area of the part-spherical combustion chamber caps.
Additional characteristics further developing the invention are indicated herein and in the claims.
According to certain preferred embodiments of the invention, for the optimal support or structural reinforcement of the part-spherical combustion chamber caps, the rib structure has a longitudinal rib penetrating the water cooling jacket.
According to certain preferred embodiments of the invention, so that, despite the longitudinal rib penetrating the water cooling jacket, an unhindered coolant flow can take place from the valve outlet side to the valve inlet side, corresponding passage openings are constructed in the longitudinal rib.
According to certain preferred embodiments of the invention, a particularly effective support or suspension of the part-spherical combustion chamber caps is ensured when the longitudinal rib is provided centrally between the valve inlet side and the valve outlet wide and is linked to the individual spark plug domes.
According to certain preferred embodiments of the invention, for the further reinforcement of the cylinder head housing, the rib structure has diagonal ribs which are linked to the domes for the cylinder head screws, the spark plug domes as well as the valve stem guides.
A particularly effective rib structure is obtained according to certain preferred embodiments of the invention, when, in addition to the longitudinal and diagonal ribs, transverse ribs are provided which mutually connect the domes for the cylinder head screws, which domes are placed in the cylinder head housing on the inlet side and the outlet side.
The drawing illustrates an embodiment of the invention which will be described in detail in the following.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.